The broad, long-term objective of this study is to determine the most effective allied health care intervention to promote health and prevent co-morbidities in people that have multiple sclerosis (MS). One of the most common interventions prescribed to promote health and prevent co-morbidities is physical therapy (PT). New and emerging strategies to promote health are called wellness interventions (Wl). Both types of intervention use different strategies to promote health and exercise, and preliminary evidence indicates that both types significantly improve the health of people who have MS. However, the strategies of both interventions have not been compared to each other. The purpose of this research application will be to compare the effectiveness of PT to Wl for people who have MS. The specific aims of the study are: 1) to determine if one type of intervention is more effective than the other in improving health and exercise adherence and to explain why, using the Theory of Planned Behavior (TPB); 2) to increase the prediction power of the TPB by introducing new psychological measurements; 3) to identify psychological factors that might predict a more effective PT or Wl. These aims will be met by a two-group pretest/posttest and follow-up randomized trial design. Fifty people with MS will be randomized into either PT or the Wl group. Outcomes will consist of measures of physical health, psychological health, exercise beliefs, and exercise adherence. By comparing the overall strategies of the two interventions, more will be known about the more efficient strategies of promoting health and exercise adherence, about whether an intervention's effectiveness depends on the psychological traits of the patient (who is the recipient of the intervention's effect), and about whether there are unique benefits to either intervention. This will provide for more efficient referrals with accompanying cost savings. The TPB is a model widely used to explain health behavior. Increasing the prediction power of TPB will help improve the understanding of how beliefs drive behavior, and thus assist in the identification of more efficient strategies to promote healthy behavior.